1. Field of Invention
This invention relates to bags, packages or packaging material which can easily be torn, without the need for scissors, for instance. In particular, although not exclusively, the invention relates to sealable plastic bags for the containment of food or beverages. However the invention is not limited in its application to food packages and may have application to other industries such as pharmaceuticals
2. Background to the Invention
The waterproof, air-tight and durable nature of plastic bags means that they are widely used for packaging goods. Various ways for facilitating the opening of such bags are known. The simplest approach is to print a line on the bag to indicate where an opening should be cut. This cut might open directly onto the contents of the package (eg FIG. 1) or it might open onto a spout integrated into the package (eg FIG. 2; see also U.S. Pat. Nos. 4,491,245, 4,793,121 and 4,935,283 and the xe2x80x9cAmpac(trademark) spout-packxe2x80x9d). Such a spout also makes a convenient opening for the insertion of a drinking straw.
Bags are also available which can be opened without the need for scissors. Whilst this can be achieved very easily by simply perforating the intended opening, this is not suitable where the package must be kept air-tight (eg liquids or perishable goods). To overcome this difficulty, it is known to integrate a guide wire or string into a package which, when pulled, opens the package (eg FIG. 3). Another system incorporates two strong parallel tracks into the plastic which define a channel between them (eg FIG. 4). The end of this channel typically contains a nick in the plastic. When tearing begins at his nick, the two tracks guide the tear down the channel, giving a straight tear.
U.S. Pat. No. 5,552,202 describes an arrangement for guiding a tear which utilises bonded strips of materials which differ in stiffness. This difference assists the breaking of the bond between the strips and guides a tear along the bond.
GB patent 1,147,846 describes how a thin strip incorporated in the body of a sheet can provide a guide for tearing. The thin strip may be either weaker or stronger than the body of the sheet. In the former case, the strip provides a weaker path through the film than the surrounding body, along which a tear is guided; where the strip is stronger, the strip can be easily torn out of the body of the sheet, thereby separating the sheet in two.
In GB patent 1,335,036, a tear is guided by incorporating a flexible reinforcement across a sheet of material. This reinforcement itself contains a localised line of weakness and a tear along the line of weakness is trotted to the attached sheet of material.
These tearing systems can also be integrated into re-sealable bags. Once the tear has been made, the bag can still be re-sealed by means of a ziplock for instance (eg FIG. 5). This gives a tamper-proof re-sealable bag.
It is an object of the invention to provide further means for facilitating the tearing of a sheet of packaging material. It is a further object of at least a preferred embodiment of the invention to provide various types of packages which can be opened easily, and also to provide easy-tear materials and packages which can be manufactured at relatively low cost.
In accordance with a first aspect of the present invention, there is provided a bag formed of one or more sheets of flexible material wherein at least one of the sheets is multi layered including an inner layer and an outer layer relative to the interior of the bag, the inner layer having at least one line of weakness with the outer layer being substantially intact along the line of weakness and tearable along the line of weakness, wherein the line of weakness extends from a first edge of the bag.
It will be understood that the bag may comprise one or more sheets. Where the invention comprises two sheets, one or both of them may be multilayered with a line of weakness present in the respective inner layers. The following references to xe2x80x9csheet(s)xe2x80x9d therefore may apply to either one sheet having the multilayered construction defined above or both sheets having this multilayered construction.
The line of weakness in the inner layer of the sheet(s) of flexible material acts as a natural guide during tearing of the material (xe2x80x9ctearing linexe2x80x9d), and can take various forms.
For example, the line of weakness may be a perforated line in the inner layer. In such a case, the individual perforations in the inner layer need not be circular in shape. It might, for instance, be a dot-dash perforation, or any interruption in the inner layer which substantially disconnects the two portions on either side of the line of weakness. As an alternative, the line of weakness may be a zone which is thinner and/or weaker than the rest of the inner layer. Furthermore, the line of weakness in the inner layer may be the interface between two pieces of material with their edges in substantial abutment. (eg see WO98/16382).
It will be apparent that, where a perforated or thin line is used to form the line of weakness, the inner layer will typically be formed from a single piece of material. Where essentially abutting pieces are used, however, the inner layer may be formed from pieces of different materials which together form the inner layer.
In preferred embodiments, the line of weakness is substantially straight.
In order to facilitate the initiation of a tear, preferred embodiments include a small opening, break, nick, notch or the like along the first edge of the bag. Suitably, the tearing line extends from the first edge of the bag to a second opposite edge. In this case, the nick may be disposed at or adjacent one end or both ends of the tearing line. Furthermore, the tearing line may be visibly indicated on the bag, for example by printing a dotted line at the relevant position.
Being situated in the inner layer, rather than the outer layer, the tearing line is less likely to break or split due to any internal pressure exerted by contents of the package. In addition, the tearing line is protected from external damage such as rubbing.
The inner layer of the flexible sheet(s) is preferably attached to the outer layer of the flexible sheet adjacent to the tearing line for substantially the length of the line of weakness.
The outer layer of the sheet(s) of flexible material can be formed from anything that can be torn. It can thus be formed from, for instance, plastic, paper, metallic film etc.
The inner and outer layers are preferably of the same size or area. The layers may extend across the whole area of the sheet(s) of flexible material.
The sheet(s) of flexible material may, however, comprise additional layers. For example, the outer layer of the sheet(s) of flexible material need not be the outermost layer of the package; nor need the inner layer be the innermost layer of the package.
Indeed, it may be desirable to ensure that the tearing line is not exposed to the contents of the package, for instance by adding a further layer to the sheet(s) of flexible material. Furthermore, if the sheet of flexible material is to be thermally bonded to another sheet of material ie laminated, it is preferred that it includes an additional layer which protects the tearing line from being sealed itself. This additional layer could, for instance, be heat-sealable at a temperature substantially below that required to melt the inner layer of material containing the line of weakness.
Sheet(s) of flexible material for use in the manufacture of bags or packages according to the invention can be produced in a number of ways. Where tie line of weakness in the inner layer is a perforated line, the sheet(s) can be formed simply by bonding two layers, one of which contains a perforated line. Alternatively, a thin band of material containing a perforation could be attached to a sheet(s) of flexible material to define the line of weakness.
Similarly, where the line of weakness is a thin zone in the inner layer, the material can be formed by bonding two layers of flexible material, one of which contains a thin zone. The thin zone can be created by infra red or laser, or by mechanical means.
International patent application WO98/16382 describes how in plastic laminates, a plurality of pieces in the form of strips may be placed with their longitudinal edges in substantially abutting relationship. The interface between abutting strips forms a line of weakness. With reference to the two-layer laminated material described in WO98/16382, layer xe2x80x9cAxe2x80x9d can form the outer layer of the flexible material used in the present invention, and layer xe2x80x9cCxe2x80x9d (formed from abutting strips) can form the inner layer.
The strips which make up layer xe2x80x9cCxe2x80x9d may be made from the same or different materials, as set out in WO98/16382 (eg alternating transparent and opaque strips, such as holographic or metallised strips). It will be appreciated tat, where two abutting strips are of the same material, they can be formed by cutting a sheet of material into two before laminating to the outer layer, where the abutting strips are of different materials, however, they will typically be supplied from separate supply rollers.
Furthermore, layer xe2x80x9cExe2x80x9d in the three-layer laminate of WO98/16382 can form a layer additional to the inner and outer layers of the present invention, to protect the tearing line from the contents of the package or during thermal bonding. FIG. 6 shows an example of a suitable sheet of material comprising three layers. It will be appreciated that, unlike the tear-guiding materials disclosed in the prior art, the present invention does not require any additional or special material to be incorporated into the bag or package in order to guide the tear, as the line of weakness is integral to the sheet(s) of flexible material. Thus, there is minimal additional production cost For example, a line of weakness can be formed simply by cutting the inner layer into two pieces, or by introducing a perforation or thin zone, before bonding to the outer layerxe2x80x94no extra material is required. Furthermore, the present invention does not rely on any difference in mechanical strength of the materials either side of the line of weakness. Nor does the line of weakness xe2x80x9cenablexe2x80x9d tearing of the packagexe2x80x94the outer layer is made of tearable material, and the line of weakness serves to control or guide the tear along a predetermined route.
In addition, the inner and outer layers of material which are used in the bags or packages of the invention may be made from any suitable flexible materials (eg plastics, paper), provided that the outer layer is tearable and the inner layer includes a line of weakness.
The bags or packages of the invention can take various forms, all of which utilise xe2x80x9cone or more sheets of tearable flexible material, with one or more of the sheets including an outer layer and an inner layer, the inner layer being provided with a line of weaknessxe2x80x9d, hereafter simply an xe2x80x9ceasy-tear sheetxe2x80x9d.
These packages will typically be over-printed with a design or pattern.
An easy-tear sheet may, for instance, be attached to a sheet of non-tearable material and sealed to form a package which can be opened along the tearing line of the easy-tear sheet. For example, the invention provides a bag having a easy-tear front sheet and a non-tearing back sheet, sealed together at or adjacent the edges of the two sheets.
Where the line of weakness is the interface between abutting pieces, the invention thus provides a bag with a front and a back, with two abutting pieces of material situated between the front and the back, the line of abutment constituting a tearing line.
Alternatively, an easy-tear sheet may be attached to another easy-tear sheet eg a bag can be formed having a front and a back each of which are easy-tear sheets. These two sheets can be positioned such that the tearing lines in the two sheets are aligned (ie essentially co-linear, but possibly deviating slightly eg within 1 mm), thus ensuring that the tear in the front and back sheets of the bag are also aligned. In the empty state of the bag the two sheets may lay directly one upon the other with the sheets sealed at or adjacent their edges.
Bags of the invention can also be produced by folding a single easy-tear sheet back on itself so that the tearing line is aligned with itself.
In addition, bags according to the invention may incorporate means for re-sealing an opened bag, such as a zip-lock In such embodiments, the tearing line should be straight.
Packages or bags of the invention are preferably sealed around the periphery of the sheets. Additionally, the sheet(s) may be sealed together adjacent the tearing line for substantially the length of the tearing line. A gusset portion may be accommodated into the bag with the sealing of the sheet(s) accommodating the gusset portion.
In one preferred form of the invention, the interior of the bag includes a main portion and a spout portion narrower than the main portion and extending beyond the main portion with the tearing line extending across the spout portion such that the spout portion is openable on tearing along the tearing line. Preferably, the spout portion is sealed closed on filling of the bag. After opening, the contents of the package may be sucked or squeezed out. The spout may also be of a size and shape which allows it to be plugged or stopped
As well as being suitable for pouring, the spout-like opening can also accept articles such as drinking straws, pipes, pumps etc. These may be included wit the sealed package where appropriate eg the sealed bag or package may include an integral drinking straw such that, when the package is torn open, the drinking straw is already immersed and ready for use. The immersed drinking straw can preferably be extended after the package is torn open.
In packages containing an immersed drinking straw, the line of weakness will typically be substantially straight, and will guide the tear away from the portion of the package containing the beverage, in order to avoid spillage.
Placing a drinking straw inside a bag or package together with a beverage offers a number of advantages eg production costs are lower, because the straw is not packaged separately; the straw will not be lost inadvertently; the straw is more hygienic, as it cannot be contaminated after it is packaged.
Packaging a drinking straw in situ with a carbonated beverage in particular offers advantages over conventional carbonated beverage packages (ie plastic bottles and cans). Although still beverages, such as orange juice, are often distributed in packages which are punctured by drinking straws in order to access the beverage, this form of packaging is not suitable for carbonated beveragesxe2x80x94due to the sudden pressure change when the package is punctured, the carbonated drink is forced out of the package through the straw, causing spillage. In the packages of the present invention, however, when the package is tom open along the tearing line, the in situ drinking straw provides a buffer zone allowing the internal and external pressures to equilibrate, thereby preventing spillage. As no puncturing operation is required, the problem of spillage caused by sudden pressure change is avoided or minimised Furthermore, flexible packages for carbonated beverages offer advantages over traditional hard containers such as production cost, storage space and cost when empty, transportation space and cost when empty, and environmental concerns.
Similarly, packaging a straw or tube or other opening within a sealed bag or package, such that the contents can leave the package via the straw or tube, offers hygienic advantages in other situations eg medical situations, where the contents of the bag and straw/tube can both be packaged in sterile conditions. When the bag is tom open, the contents can be accessed easily, without the need to introduce a potentially-contaminated straw/tube from an external source.
The sheets of flexible material used to produce bags or packages of the invention may comprise more than one line of weakness. Where a single sheet comprises two parallel lines of weakness, for instance, the sheet is, in effect, divided into three strips, the middle of which may easily be removed or separated from the bag. The easy-tear sheet may thus be in the form of a cover for a bag or package, a strip of which can be torn away to give access to the contents of the bag or package. Each pair of tearing lines allows a separate strip of the sheet to be removed, each of which can give access to a different region of the package.
The package may contain a plurality of separate internal compartments. Partitions may be provided between adjacent compartments. The partitions may be created by sealing the two sheets together at the locations corresponding to the partitions. If a tearing line crosses the partition between two separate compartments, both compartments can be opened with one tear. If it is desired to halt the tear between opening successive compartments, this can be achieved by, for instance, providing a slight break in the tearing line.
Furthermore, means for assisting the removal of portions of the bag which have been opened may be incorporated. For instance, if perforations are included which are within the partition between two compartments and which cross the tearing line, the tear will tend to halt when it meets the perforation, and the torn part of the package can be removed by tearing along the perforated line, rather than along the tearing line. Alternatively, in certain embodiments, the perforated line could be torn first, stopping when the tearing line has been crossed, followed by tearing along the line of weakness. In this case, the junction between the perforation and the tearing line acts as a nick for facilitating initiation of the tear. Where a tear starts from the edge of the package, the tear can still be initiated, although a little more force may be required.
Packages of the invention are also suitable for storing liquids, such as beverages. In a preferred embodiment, the package of the invention comprises a first and a second sealed internal compartment. The first sealed internal compartment contains a drinking straw which can be accessed by removing a portion of the package along the package""s tearing line. The second sealed internal compartment contains a beverage. The beverage is not accessed via the tearing line used to access the drinking straw, however, but by puncturing the package using the drinking straw. Thus the package contains a beverage and a drinking straw, with the straw stored in sanitary conditions within the package, preventing its inadvertent loss, but separate from the beverage. In addition, the tear is guided without tearing the package such that the beverage spills, This approach to packaging a drinking straw is a less-preferred alternative to the xe2x80x9cimmersed strawxe2x80x9d approach described above.
In accordance with a second aspect of the present invention, there is provided a bag formed of one or more sheets of flexible material wherein at least one of the sheets is multi layered including an inner layer and an outer layer relative to the interior of the bag, the inner layer including two pieces with substantially abutting edges and having at least one line of weakness which is defined by the interface of the two pieces with the outer layer being substantially intact along the line of weakness and tearable along the line of weakness.
The interface between the abutting pieces creates in effect a thin straight channel (xe2x80x9ctearing linexe2x80x9d) in the bag, along which a tear is naturally guided This allows the bag to be opened easily.
If desired, there may be more than one layer of abutting pieces between the front and the back of the bag. For instance, a bag could be formed from two sheets of laminated plastic material, both of which comprise a layer consisting of abutting pieces of material. These two sheets can be juxtaposed such that the layers comprising abutting pieces are both between the front and back of the bag, with their lines of abutment aligned (ie essentially co-linear, but possibly deviating slightly eg within 1 mm). This creates, in effect, a composite tearing line.
A suitable laminated plastic material which contains a tearing line is one which may be made using the method as disclosed in International Patent Application WO98/16382 as discussed previously. Briefly, the laminated plastic comprises a base layer onto which are adhered a plurality of parallel strips of material which abut and do not overlap. An example of a suitable laminated plastic material, which also comprises a third layer, such that the abutting parallel strips are sandwiched, is shown in FIG. 6, and this type of material is used in the most preferred embodiments of the invention.
In preferred embodiments, one end or both ends of the tearing line contains a small opening, break, nick, notch or the like. This facilitates the initiation of a tear. The tearing line may be visibly indicated on the bag, for example by printing a perforated line at the relevant position.
The bag is preferably sealed at or adjacent its edges. In one preferred form of the invention, the interior of the bag includes a main portion and a spout portion narrower than the main portion and extending beyond the main portion with the tearing line extending across the spout portion such that the spout portion is openable on tearing along the tearing line. Preferably, the spout portion is sealed closed on filling of the bag. After opening, the contents of the package may be sucked or squeezed out. The spout may also be of a size and shape which allows it to be plugged or stopped.
It will be appreciated that the sheet(s) of flexible material which are used to make the bag may comprise more than two layers. For instance, whilst they might comprise just a base layer and a layer of abutting parallel strips, they might also comprise a further layer, covering and protecting the abutting parallel strips, for instance. Suitably, the layers of each of the sheets will be laminated together. Furthermore, the sheets will typically be over-printed with a design or pattern. The front and back of the bag need not, of course, be made from the same material.
The parallel abutting pieces within the laminated plastic may be made from the same or different material. For instance, both pieces could be transparent, or one strip could be metallised whilst the other is transparent.
In addition, bags according to the invention may incorporate means for re-sealing an opened bag, such as a zip-lock.
In accordance with a third aspect of the present invention, there is provided an enclosure or package formed of two overlapping sheets of flexible material wherein, in an empty state of the enclosure or package, the two sheets lay one directly upon the other, and wherein at least one of the sheets is multi layered including an inner layer and an outer layer relative to the interior of the enclosure or package, the inner layer having at least one line of weakness with the outer layer being substantially intact along the line of weakness and tearable along the line of weakness.
Preferably first and second lines of weakness are formed on respective ones of the sheets, the lines of weakness being aligned.
In accordance with a fourth aspect of the present invention there is provided an enclosure or package formed of one sheet of flexible material folded back on itself to define two sheet portions wherein, in an empty state of the enclosure or package, the two sheet portions lay one directly upon the other and wherein the sheet is multi layered including an inner layer and an outer layer relative to the interior of the enclosure or package, the inner layer having at least one line of weakness with the outer layer being substantially intact along the line of weakness and tearable along the line of weakness.
Preferably first and second lines of weakness are formed on respective sheet portions, the lines of weakness being aligned.
In accordance with a fifth aspect of the present invention there is provided a bag formed of two overlapping sheets of flexible material wherein at least one of the sheets is multi layered including an inner layer and an outer layer relative to the interior of the bag, the inner layer having a first line of weakness with the outer layer being substantially intact along the first line of weakness wherein the other sheet also includes a second line of weakness substantially aligned with the first line of weakness such that the bag is tearable along the two lines of weakness.
In accordance with a sixth aspect of the present invention there is provided a bag formed of one sheet of flexible material folded back on itself to define two sheet portions wherein at least one of the sheet portions is multi layered including an inner layer and an outer layer relative to the interior of the bag, the inner layer having a first line of weakness with the outer layer being substantially intact along the first line of weakness wherein the other sheet portion also includes a second line of weakness substantially aligned with the first line of weakness such that the bag is tearable along the two lines of weakness.
In accordance with a seventh aspect of the present invention, there is provided a bag formed with a front and back and a straight line of weakness formed between the front and the back such that the bag is tearable along the line of weakness, the bag further having a strip of flexible material inserted between the front and the back, the strip extending substantially parallel to the line of weakness such that the strip is adapted to function as a handle when the bag is torn along the line of weakness.
Preferably the bag is formed of one sheet of flexible material folded back on itself to define two sheet portions wherein at least one of the sheet portions is multi layered including an inner layer and an outer layer relative to the interior of the bag, the inner layer incorporating the line of weakness with the outer layer being substantially intact along the line of weakness.
Alternatively, the bag may be formed of two overlapping sheets of flexible material wherein at least one of the sheets is multi layered including an inner layer and an outer layer relative to the interior of the bag, with the inner layer incorporating the line of weakness with the outer layer being substantially intact along the line of weakness.
Preferably, the bag includes a gusset portion formed at an end of the bag opposite to the strip when the bag has been torn along the line of weakness.
In accordance with an eighth broad aspect of the present inventions, there is provided a multi layer packaging material having a first layer and a second layer wherein the first layer includes two pieces with substantially abutting edges and having at least one line of weakness which is defined by the interface of the two pieces with the second layer being substantially intact along the line of weakness and tearable along the line of weakness.